I created slope map with DEM model in ArcGIS Desktop. But it is only categorize in to two sections. I think it is problem with the horizontal and vertical scale. I used WGS84 coordinate system.
How do I overcome this problem?
Supply a z-factor in your slope tool parameters to convert your elevation units (I assume meters) to the horizontal coordinate units of your DEM (degrees).
From the documentation:
The z-factor is a conversion factor that adjusts the units of measure for the vertical (or elevation) units when they are different from the horizontal coordinate (x,y) units of the input surface. It is the number of ground x,y units in one surface z-unit. If the vertical units are not corrected to the horizontal units, the results of surface tools will not be correct.
Latitude Z-factor 0 0.00000898 10 0.00000912 20 0.00000956 30 0.00001036 40 0.00001171 50 0.00001395 60 0.00001792 70 0.00002619 80 0.00005156
Note that as the range of latitude in your raster data increases, the more approximate the results will be.